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Explicit internal signal stochastic resonance (EISSR) is investigated in a model of energy transduction of molecular machinery when noise is added to the region of oscillation in the presence of external signal (ES). It is found that EISSR could be controlled, i.e., enhanced or suppressed by adjusting frequency (ωe) and amplitude (A) of ES, and that there exits an optimal frequency for ES, which makes EISSR strength reach the maximum. Meanwhile, a critical amplitude (Ac) is found, which is a threshold of occurrence of EISSR. Finally, the difference and similarity between EISSR and IISSR (implicit internal signal stochastic resonance) are discussed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Internal stochastic resonance (ISR) in a model of intercellular calcium ion oscillations is investigated under the modulation of two parameters, viz., degree of extracellular stimulation (β) and leak rate (kf). ISR can occur when either β or kf is subjected to a noise. Internal stochastic biresonance (ISBR) can occur when noise is added to the two parameters simultaneously. The distance to the bifurcation point is found to be able to enhance or suppress the ISBR, and to affect the number of peaks of ISR. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Responses of Ca2+ oscillations to random perturbation are investigated at the conditions where the system stays at a steady state (before bifurcation point) or an oscillatory state (after bifurcation point). It is found that noise can induce both implicit and explicit internal signal stochastic resonance (IISSR and EISSR). In particular, the internal signal stochastic bi-resonance is also observed. When an external signal is added to the system, no IISSR or EISSR phenomenon occurs, implying an external signal destroys cooperation of Ca2+ signal and environment noise. [Copyright &y& Elsevier]

Explicit internal signal stochastic resonance (EISSR) is investigated numerically when noise is added to the region of periodic-2 oscillatory state in intercellular calcium ion oscillations. It is found that the signal-to-noise ratio (SNR) of strong signal (SS) has a maximum value at an optimal noise intensity and that of weak signal (WS) increases monotonously with the increment of noise intensity. These results indicate that the EISSR has selectivity to two intrinsic signals of system. Moreover, the frequencies of SS and WS hardly change, which implies that system can resist to the effect of noise and sustain intrinsic period oscillatory states. [Copyright &y& Elsevier]

Internal stochastic resonance (ISR) in a liquid membrane oscillator is investigated by varying frequency (ωs) and amplitude (A) of an external signal (ES) in the presence of environment noise. It is found that the enhancement or suppression of ISR depends on frequency and amplitude of ES. In the range of low frequency (0.03–0.12 Hz), ISR appears and noise can transfer energy of ES to IS both for A=0.02 M and for A=0.15 M. In the range of high frequency (0.26–0.32 Hz), there exits an optimal frequency for ES, which is equal to frequency of IS and makes ISR strength reach maximum for A=0.02 M; but ISR disappears for A=0.15 M. At the optimal frequency ωs=0.28 Hz, a critical amplitude Ac for ES is found, less than which, ISR appears, and more than which, ISR disappears. [Copyright &y& Elsevier]